The present invention relates to sheet sorter apparatus and particularly to a machine for sorting sheets produced by a duplicator, such as a xerographic copier, and arranging or collating such sheets into sets.
Sorter apparatus embodying the invention is especially suitable for use with compact xerographic copiers in order to sort the number of duplicate copies of the same sheet which such copiers are designed to produce, for example, up to approximately ten or twenty sheets. Other applications for the invention may be found wherever automatic sorting and collating of sets of sheets is desired.
Sorters have generally been large and complex machines. Because of their size they have not been adapted for use with small, so-called desk top xerographic copiers. It is desirable to provide sorting facilities for the smaller copiers having the capabilities of the large, complex sorters, but of a size and at a cost which is comparible with the smaller copiers. It has been proposed to use a stack of trays and drop the trays successively out of the stack so that they move through a location aligned with the exit feed rollers of the copier. The bidirectional sorting capability of the larger copiers has not been maintained. For example, the entire stack of trays must be indexed onto starting position before each group of like copies can be sorted. Sorting speeds are lower than is the case for the large sorters. Moreover, drop mechanisms are subject to failure and tend to be noisy.
It is therefore an object of the present invention to provide improved sorter apparatus which is compatible, and adapted for use, with small, desk top type copiers.
It is the further object of the invention to provide improved sorter apparatus which is compact in size and has the capability of distributing a number of sheets into a set, similar to that of larger sorters.
It is a still further object of the present invention to provide improved sorter apparatus utilizing a stack of trays into which sheets are distributed which trays are bidirectionally movable into and out of position to receive sheets from a duplicator, copier or sheet feeding device associated therewith.
It is a still further object of the present invention to provide improved sorter apparatus which does not rely on gravity and is positively moved in the course of sheet distributing operations.
It is still a further object of the present invention to provide improved sorter apparatus in which the generation of noise during operation is minimized.
It is a still further object of the present invention to provide improved sorter apparatus which is simple and reliable and may be implemented at low cost.
Briefly described, sheet sorting apparatus embodying in the invention makes use of a plurality of sheet receiving trays which are disposed in a stack. The trays are retained in stacked relationship by means which are movable therewith. The stack may, for example, be movable in a generally vertical direction upwardly and downwardly. The retaining means for the stack of trays may be located at the sides of the trays near the front end thereof where the sheet feeder, such as the exit feed rolls of the copier associated with the sorting apparatus, is located. The rear ends of the trays can be loosely disposed on the shelves of a rack so as to enable translational and pivotal movement of the rear ends of the trays. Guide means which also may be located along the sides of the trays near the front ends thereof, provide the path along which the trays are moveable. This path includes a region where adjacent ones of the trays are spread apart to receive the sheets. The retaining means is operative to locate and register adjacent trays at opposite ends of the region, and provides a carriage for the stack of trays. In order to move the trays, and the stack of trays, either upwardly or downwardly, means are provided which are engagable with the tray at one end of the sheet receiving region or with the tray at the opposite end of that region to carry the engaged tray between the ends of the region. As the engaged tray moves, the retaining means and the stack of trays together with the engaged tray also move along the path defined by the guide means. The sheet receiving region of the path over which the trays are carried may be semicircular. Each tray may be engaged by an orbiting member driven by a crank mechanism so as to carry it between the opposite ends of the region. The stack is confined in the retaining means, such that when the crank mechanism moves (lifts or lowers) a tray along the sheet receiving region, it transfers forces through the stack to the retaining means so as to enable the retaining means to lift or lower the entire stack. Bidirectional operation is therefore obtained with lifting or lowering operations of the crank mechanism being carried out for each sheet which is fed into the sorting apparatus.